Engine distributor spark advance system

ABSTRACT

An internal-combustion engine has an ignition spark advance system that includes a valve controlling either a supply of air at atmospheric pressure to the vacuum servo moving the spark advance lever, or subjecting the servo to changing intake manifold vacuum; the valve being connected to and movable with the vehicle accelerator pedal; the valve body in which the valve slides being connected to the carburetor throttle valve; the system including a dashpot permitting slow closing of the throttle valve upon deceleration while simultaneously retarding the spark.

United States Patent [72] Inventor Francis P. Hutchins Livonia, Mich. [211 Appl. No. 758,238 [22] Filed Sept. 9, 1968 [45] Patented Aug. 3, 1971 (73] Assignee Ford Motor Company Deal-born, Mich.

[541 ENGINE DISTRIBUTOR SPARK ADVANCE SYSTEM 2 Claims, 1 Drawing Fig.

[52] U.S.Cl 123/117, 123/97 [51] Int. Cl. F02 S/04, F02d 31/00 [50] l-ieldoisearch l23/ll7.l, 97 B [56] Referenea Cited UNITED STATES PATENTS 2,229,822 1/ 1941 Seymour 123/ 1 17.1

3,289,659 12/1966 Koole 123/1 17.1

2,867,197 1/1959 McCollough... 123/1 17.1

3,046,962 7/1962 Norris 123/117 1 3,162,184 12/1964 Walker 123/! 17.1

3,252,450 5/1966 Dietrich et al. .123/1 171 OTHER REFERENCES 1961 Ford Service Manual, Ford Motor Co. pages 2- 11, I

Primary ExaminerMark M. Newman Assistant Examiner-Ronald B. Cox Attorneys-John R. Faulkner and Robert E. McCollum PATENTEU AUG 3 H?! ww mm MW Wm NW M Wm INVENTOR Fi/I/1 (/5 P A Z/TCH/A/S ATTORNEYS ENGINE DISTRIBUTOR SPARK ADVANCE SYSTEM This invention relates, in general, to a motor vehicle engine ignition system. More particularly, it relates to an engine spark advance and retard system that automatically controls the distributor spark advance or retard as a function of the changing conditions of operation of the engine.

Most automotive internal-combustion engines have some sort of an ignition spark advance or retard mechanism to automatically advance the spark as the speed of the engine in creases to compensate for the constant burning rate of the fuel-air mixture. That is, some device must be provided that automatically ignites the air-fuel mixture sooner with a higher engine speed than before so that the fuel-air mixture, which has an essentially constant burn rate, will burn properly. This device has taken the form of a vacuum servo or motor that has a connection to the carburetor induction passage just above the idle speed position of the throttle valve. As engine speed increases, as indicated by opening movement of the throttle valve, the spark port is exposed to increasing vacuum, which advances the spark proportionally. During idle, the vacuum signal generally is cut off, and the return spring in the servo moves the distributor spark advance lever to a retard position.

A dashpot is often associated with a system of this type so as to retard the closing movement of the throttle valve during decelerations to prevent stalling of the engine. Upon decelerations of the vehicle from high speeds, however, the slowly closing throttle valve maintains vacuum on the advance diaphragm and thereby maintains the distributor spark advanced. This furnished more power to the vehicle than is desired or necessary, and reduces engine-braking effort.

An advantage does, however, exist with the use of a dashpot. During normal operation of the engine, with the throttle opened, the flow of fuel and air through the induction passage wets the passage completely with fuel. W hen the throttle valve is quickly closed to its idle speed position, therefore, rich mixture is present in the intake manifold. This may become a source of unburned hydrocarbons. At this time, the only air being brought into the induction passage is through the idle system, and since this supply is low, not enough air generally, therefore, will be added to the system to dilute the rich mixture sufficiently to prevent unburned hydrocarbons from being emitted into the air through the exhaust system.

The use of a dashpot maintains the throttle valve in an off idle position for a longer period of time during deceleration. When the throttle valve is operating at off idle position, the carburetor is normally calibrated for a leaner mixture; accordingly, air added at this time generally will be sufiicient to dry out the intake manifold passage and, therefore, significantly reduce the possibility of unburned hydrocarbons being passed into the atmosphere.

The invention utilizes the I advantageous features while eliminating the above disadvantages by providing a spark advance and retard system that maintains the spark retarded to its desired maximum amount during idle speed and deceleration conditions of the engine, while only slowly closing the throttle during decelerations, and yet automatically advances the spark as a function of the increase in vacuum occasioned by rotation of the throttle valve from its idle speed position.

More specifically, the invention includes a vacuum signal switch between the carburetor spark port and the distributor spark advance vacuum servo that is operatively moved upon release of the vehicle accelerator pedal to block the vacuum signal to the servo diaphragm during decelerations; while, however, permitting the action of a dashpot to slowly close the throttle valve and thereby lean out what would normally be a rich mixture in the carburetor passage. Depression of the throttle pedal automatically moves the vacuum signal switch to again connect the vacuum spark port and the advance diaphragm to automatically advance the spark in accordance with increases in engine speed and manifold vacuum.

It is an object of the invention, therefore, to provide a distributor vacuum spark advance and retard system that includes a switch means having relative movable parts connected both to the carburetor throttle valve and the vehicle accelerator pedal for controlling the flow of vacuum to the ad vance diaphragm as a function of engine-operating conditions.

Other objects, features, and advantages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating schematically a cross-sectional view of a distributor spark advance and retard system embodying the invention.

The FIGURE shows a portion 10 of the induction passage in a known type of downdraft carburetor. it contains the usual main or primary venturi section 12 and a booster venturi l4 discharging (by means not shown) a fuel-air mixture into passage 10. Flow of the air-fuel mixture through passage 10 is controlled by a rotatably mounted throttle valve 16. The lower passage portion 18 is adapted to be connected to the intake manifold (not shown) of the engine.

Valve 16 is shown in its engine idle speed position essentially closing passage 10, and cutting off the intake manifold vacuum signal to a spark port 20 located just above the idle speed position of throttle valve 16. Port 20 is connected by a line 22 through a control valve 24 and a line 26 to a vacuum servo 23. Servo 28 controls the spark advance or retard setting of a distributor 30. Control valve 24 will be described in more detail later. Suffice it to say at this point that it alternately applies vacuum from spark port 20 or air at atmospheric pressure to line 26 to automatically control the spark advance mechanism of distributor 30.

The details of construction and operation of distributor 30 are known and believed to be unnecessary for an understanding of the invention. Suffice it to say that the distributor has the usual spark advance lever, not shown, secured to the diaphragm illustrated schematically at 32 in servo 28. The diaphragm divides the servo into an air chamber 33 on the right-hand side, and a second chamber 34. It is biased by a spring 36 towards the distributor to an initial maximum desired spark retard position. Leftward movement of the diaphragm 32 by a vacuum in chamber 34 moves the spark advance lever to automatically advance the spark in proportion to the change in vacuum.

The valve control 24 has a cylindrical or similarly shaped valve body 38 fixedly secured to a rod 40. Rod 40 is pivotally connected to one end of a link 42 that, at its opposite end, is fixedly secured to the throttle shaft 44 so the two have a unitary rotation. Valve body 38 contains an essentially cylindrical bore 46 that slidably receives therein a ball valve member 48. The ball valve cooperates by alternately seating against a pair of spherically shaped valve ports 50 and 52 connected respectively to a pair of fluid passages 54 and 56. Each of the valve ports or seats contains a resilient o-ring-type sealing member 58 that compresses upon engagement of the ball valve therewith to seal the adjacent passage. Passage 54 is connected to vacuum tube 22, while passage 56 is open, as indicated, to air at ambient pressure or atmospheric, as the case may be.

Valve body 38 has a pair of angled passages 60 that are joined at their outer ends to the tube 26, and at their inner ends are each directed at one of the valve seats 50 and 52. The annular valve body portion 64 defined between passages 60 and 62 serves as a guide for the movement of ball valve 48 in an axial direction, and minimizes misalignments at the O-ring seats. it also provides fluid interconnection between seats 50 and 52 and the tube 26 through the passages 60 and 62 rather than around the ball valve 48.

Ball valve 48 is fixed to a rod or shaft 66 that is pivotally connected at 68 to one end of a conventional accelerator pedal mounted lever 70. The latter is pivotally mounted near its midpoint at 72, and contains a pivotally mounted pad 74 at its lower extremity. The ball valve rod 66 has an extension 76 secured by a throttle valve or accelerator return spring 78 to a stationary portion 80 of the engine.

Finally, a conventional slow return dashpot 82 having a rod 84 projects into the path of movement of throttle lever link 42 so as to be contracted thereby upon movement of the link 42 in a leftward or throttle valve closing direction. The details of construction and operation of the dashpot are not given since they are known and believed to be unnecessary for an understanding of the inventidn. Suffice it to say that the dashpot operates in a conventional manner providing a slow movement of rod 84 in a leftward direction, but a fast movement in the opposite direction.

In operation, with the engine idling, the parts will be in the positions shown. Throttle valve 16 will be in a closed position essentially cutting off the vacuum in the intake manifold passage portion 18 to spark port 20 and tube 22. Also, the accelerator pedal return spring 78 will have moved ball valve 48 to seat against O-ring seal seat 50 blocking tube 22. Simultaneously, this moves the valve body 38 and rod 40 to the left to position the throttle valve 16 as shown.

Air at atmospheric or ambient pressure enters through passage or port 56, passes through port 52 and passage 60 into tube 26. It then balances the air pressure in servo chamber 33 and permits the force of spring 36 to move the distributor advance lever to its maximum retard position. Therefore, during engine idle speed operation, the distributor will be in the desired maximum spark retard position.

When the accelerator pedal 74 is depressed leftwardly, rod 66 and ball valve 48 are moved to the right to seat the ball valve against O-ring 58 and close the atmospheric air line 56. Simultaneously vacuum line 54 is opened to tube 26. At the same time, continued rightward movement of ball valve 48 moves valve body 38 to crack open throttle valve 16 and admit vacuum in passage portion 18 to tube 22. This, of course, immediately acts on the advance diaphragm 32 to begin advancing the distributor spark. Accordingly, the spark will be advanced in proportion to the opening of the throttle valve 16 to a maximum value desired.

During deceleration, accelerator pedal 74 is released, permitting return spring 78 to immediately move ball valve 48 to engage seat 50, closing vacuum line 22 and opening atmospheric line 56, to permit servo spring 36 to immediately move the distributor spark advance lever to the maximum retard position. At the same time, the leftward movement of ball valve 48 moves valve body 38 leftwardly in an attempt to close throttle valve 16 quickly. However, the dashpot rod 84 is engaged by link 42 when moving from the dotted line position indicated so that the throttle valve only closes slowly during this period. Therefore, while vacuum is still being admitted from the intake manifold to tube 22, it is of no effect on the advance diaphragm since it is cut off from the tube 26 by seating of ball valve 48 against seat 50. Accordingly, the slowly closing throttle valve will permit a drying out of the carburetor induction passage so that a much leaner mixture exists therein and one that can be efiiciently burned in the combustion chamber so as to minimize the passage of unburned hydrocarbons into the exhaust system.

From the foregoing, therefore, it will be seen that the invention provides a distributor spark advance and retard mechanism that automatically provides a correct ignition advance or retard as a function of engine-operating conditions, while at the same time controlling the carburetor throttle valve during deceleration so as to minimize the formation of unburned hydrocarbons in the exhaust system of the engine.

While the invention has been illustrated in its preferred embodiment, it will be clear to those skilled in the arts to which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention.

lclaim:

l. Distributor spark advance and retard control means for an intemal-combustion engine comprising, in combination, a carburetor induction passage connected at one end to the intake manifold of said engine and to a source of fuel and air at the opposite end and having a venturi and a throttle valve rotatably mountedjn said passage posterior of said venturi and movable from an idle speed position to variably control the flow of an air-fuel mixture through said passage, a spark control port connected to said passage on the air inlet side of said valve when in an idle speed position, said port being subjected at all times to vacuum from said manifold upon movement of said valve from said idle position, an operator movable accelerator means movable from a closed at rest position towards a wide-open throttle position, a distributor spark advance and retard vacuum servo actuator, first conduit means connected to said servo actuator, second conduit means connected to said spark port, and valve means interconnecting said conduit means and controlling flow of fluid therethrough, said valve means including a valve body secured to said throttle valve for movement thereof, a control valve variably movable within said valve body between one position connecting the vacuum at said spark port to said servo actuator to advance the spark timing as a function of changes in vacuum level and a second position connecting said servo actuator to air at essentially atmospheric pressure to retard said spark timing by blocking the vacuum to said second conduit means, linkage means connecting said control valve to said operator movable accelerator means, spring means operatively connected to and biasing said control valve to said second position and operatively biasing said throttle valve to said idle speed position, movement of said accelerator means in a throttle valve opening direction moving said control valve to said one position to advance said spark and also operatively moving said valve body to move said throttle valve away from said idle position to increase the vacuum level to said servo, second linkage means securing said valve body to said throttle valve, and time delay means in the path of movement in a throttle valve closing direction of said second linkage means engageable by said second linkage means upon movement of said accelerator pedal and first linkage means towards a closed position, the movement of said accelerator pedal to its closed position from an open position immediately moving said control. valve to block the vacuum in said spark port from said servo and connect air to said servo while said time delay means is simultaneously slowly retarding the closing of said throttle valve to permit continued air flow through the carburetor induction passage to dry said passage.

2. A control as in claim 1, said time delay means comprising a dashpot having a stem engageable by said linkage means. 

1. Distributor spark advance and retard control means for an internal-combustion engine comprising, in combination, a carburetor induction passage connected at one end to the intake manifold of said engine and to a source of fuel and air at the opposite end and having a venturi and a throttle valve rotatably mounted in said passage posterior of said venturi and movable from an idle speed position to variably control the flow of an air-fuel mixture through said passage, a spark control port connected to said passage on the air inlet side of said valve when in an idle speed position, said port being subjected at all times to vacuum from said manifold upon movement of said valve from said idle position, an operator movable accelerator means movable from a closed at rest position towards a wide-open throttle position, a distributor spark advance and retard vacuum servo actuator, first conduit means connected to said servo actuator, second conduit means connected to said spark port, and valve means interconnecting said conduit means and controlling flow of fluid therethrough, said valve means including a valve body secured to said throttle valve for movement thereof, a control valve variably movable within said valve body between one position connecting the vacuum at said spark port to said servo actuator to advance the spark timing as a function of changes in vacuum level and a second position connecting said servo actuator to air at essentially atmospheric pressure to retard said spark timing by blocking the vacuum to said second conduit means, linkage means connecting said control valve to said operator movable accelerator means, spring means operatively connected to and biasing said control valve to said second position and operatively biasing said throttle valve to said idle speed position, movement of said accelerator means in a throttle valve opening direction moving said control valve to said one position to advance said spark and also operatively moving said valve body to move said throttle valve away from said idle position to increase the vacuum level to said servo, second linkage means securing said valve body to said throttle valve, and time delay means in the path of movement in a throttle valve closing direction of said second linkage means engageable by said second linkage means upon movement of said accelerator pedal and first linkage means towards a closed position, the movement of said accelerator pedal to its closed pOsition from an open position immediately moving said control valve to block the vacuum in said spark port from said servo and connect air to said servo while said time delay means is simultaneously slowly retarding the closing of said throttle valve to permit continued air flow through the carburetor induction passage to dry said passage.
 2. A control as in claim 1, said time delay means comprising a dashpot having a stem engageable by said linkage means. 